Amtrak Northeast Regional operates a train from New York to Allentown hourly. Tickets cost $70 - $190 and the journey takes 55 min. Alternatively, Academy Bus LLC operates a bus from New York to Allentown hourly. Tickets cost $18 - $20 and the journey takes 1 h 30 min.
From New York Penn Station train to Trenton Transit Center Amtrak then taxi to Allentown. 1 h 9 min $164. From New York, NY - Port Authority Bus Terminal bus to Jackson, NJ - Park & Ride then taxi to Allentown. 1 h 44 min $80. From New York drive to Allentown. 1 h 2 min $6.